1. Field of the Invention
The present invention relates to a liquid crystal display, and more particularly, to a system for fabricating a liquid crystal display using liquid crystal dropping and a method of fabricating a liquid crystal display using the same.
2. Discussion of the Related Art
As information society develops, demands for various types of displays increase. Lately, many efforts are made to study and develop various panel displays such as LCD(liquid crystal display), PDP(plasma display panel), ELD(electroluminescent display), VFD(vacuum fluorescent display), and the like. And, some of such panel displays are already used for various devices and appliances.
With characteristic advantages of excellent image quality, lightness, slim size, and low power consumption, LCD, one of the panel devices, has been widely used so as to replace CRT(cathode ray tube) as a mobile image display. Besides the mobile usage for a monitor of a notebook computer, LCD is also developed as a monitor for computer, television, or the like so as to receive and display broadcasting signals.
In spite of various technical developments to perform a role as an image display in various fields, an effort to improve image quality of LCD inevitably becomes contrary to the above characteristics and advantages in some aspects. In order to use LCD for various fields as a general image display, the development of LCD depends on the facts that the characteristics of lightness, slim size, and low power consumption are maintained and that image of high quality including definition, brightness, large-scaled area, and the like is realized properly.
Such an LCD is mainly divided into a liquid crystal display panel displaying an image thereon and a driving unit applying a drive signal to the liquid crystal display panel, in which the liquid crystal display panel includes first and second glass substrates bonded to each other so as to have a predetermined space therebetween and a liquid crystal layer injected between the first and second glass substrates.
Namely, the first and second glass substrates are bonded to each other so as to provide a predetermined space therebetween using a spacer, and then liquid crystals(hereinafter abbreviated LC) are injected in the space.
In this case, the liquid crystals are injected in a manner that the a vacuum state is maintained between the two substrates, a liquid crystal injection inlet is dipped in a liquid crystal solution, and the liquid crystals are injected in the space by osmotic pressure. After completion of the liquid crystal injection, the liquid crystal injection inlet is sealed with a sealant.
Yet, such a general liquid crystal injection method for fabricating a liquid crystal display has the following disadvantages or problems.
First of all, it takes too much time for liquid crystal injection to reduce productivity since the liquid crystals are injected therein by maintaining the vacuum state between the two substrates.
Secondly, in fabricating a large-sized liquid crystal display, the liquid crystal injection method fails to fill completely an inside of the panel with liquid crystals so as to bring about failure.
Finally, the process becomes so complicated to waste process time as well as requires a plurality of liquid crystal injection instruments to fail to save a space.
Eventually, many efforts are made to study and develop LCD fabrication methods using liquid crystal dropping. One of such methods is disclosed in Japanese Patent Laid-Open No. 2000-147528 as follows.
FIGS. 1A to 1F illustrate cross-sectional views of an LCD process using liquid crystal dropping.
Referring to FIG. 1A, a UV hardening type sealant 1 is coated on a first glass substrate 3 on which a thin film transistor array is formed, and then liquid crystals 2 are dropped on an inside(thin film transistor array) of the sealant 1. In this case, the sealant 1 is formed thereon without a liquid crystal injection inlet.
The first glass substrate 3 is mounted on a table 4 in a vacuum container C which is movable in a horizontal direction, and an entire face of a lower surface of the first glass substrate 3 is fixed by vacuum suction using a first sucking instrument 5.
Referring to FIG. 1B, an entire face of a lower surface of a second glass substrate 6 on which a color filter array is formed is fixed by vacuum suction using a second sucking instrument 7, and the vacuum container C is closed for providing a vacuum state. The second sucking instrument 7 is then moved downward in a vertical direction so as to adjust a distance between the first and second glass substrates 3 and 6, while the table 4 on which the first glass substrate 3 is mounted is moved in a horizontal direction so as to adjust locations of the first and second glass substrates 3 and 6 preliminarily.
Referring to FIG. 1C, the second sucking instrument 7 is moved downward so as to contact the second glass substrate 6 with the liquid crystals 2 or sealant 1.
Referring to FIG. 1D, the table 4 on which the first glass substrate 3 is mounted is moved in a horizontal direction so as to match the positions of the first and second glass substrates 3 and 6 with each other.
Referring to FIG. 1E, the second sucking instrument 7 is moved downward in a vertical direction so as to bond the second glass substrate 6 to the first glass substrate 3 through the sealant 1 as well as pressurize the first glass substrate 3.
Referring to FIG. 1F, the bonded first and second glass substrates 3 and 6 are taken out of the vacuum container C, and then the sealant 1 is hardened by irradiating UV rays thereon so as to complete a liquid crystal display.
Yet, the LCD fabrication method using liquid crystal dropping according to the related art has the following disadvantages or problems.
First, the sealant and liquid crystals are formed and dropped on the same substrate, respectively so as to require a relative long process time.
Second, the sealant is coated on the first substrate as well as the liquid crystals are dropped on the first substrate, while no process is carried out on the second substrate. Hence, there is unbalance between processes for the first and second substrates, thereby failing to operate a product line effectively.
Third, because the sealant is coated on the first substrate as well as the liquid crystals are dropped on the first substrate, it is unable to clean the substrate coated with the sealant in a cleaning equipment(USC). Hence, the sealant bonding the substrates to each other is unable to be cleaned to remove particles therefrom, thereby bringing about failure caused by the particles in the sealant on bonding.
Fourth, when the first and second substrates are being bonded to each other, a sealant pattern is metamorphosed by being pressurized by an external force.
Fifth, it is difficult to drop a precise amount of the liquid crystals on dropping, excessive charge of the liquid crystals makes the liquid crystals run down, and insufficient charge of the liquid crystals varies a cell gap so as to affect an image quality.